Blueprint of Life Flashcards
what is the genotype of pure breeding plants?
homozygous
What did Walter Sutton (1902) find?
Studied chromosomes in testis of grasshoppers. He found that:
- chromosomes carry genes,
- random segregation and independent assortment (suggested by Mendel) relate to chromosomes separating and sorting into gametes.
- Chromosomes occur as homologous pairs
- Each chromosome carries many genes
What did Theodore Boveri (1900) find?
Studied meiosis in sea urchins and found:
- Chromosomes are in the nucleus
- a complete set of chromosomes is needed for normal development of an organism.
- Gametes contain half the normal amount of chromosomes.
- Following fertilisation there are full sets of chromosomes and then organism grows. This also showed the importance of chromosomes and that not all chromosomes are the same.
What did Thomas Morgan do?
Bred fruit flies, (drosophilia) to study genetics. 1910*
- Crossed white male with red female.
- Crossed red male with red female from F1 generation.
- Crossed white male with heterozygous red female.
The results did not follow normal mendellian genetics/ratios. He suggested the results occurred because the gene was carried on the X chromosome. This helped confirm the link between chromosomes and inheritance.
What did Mendel (in 1860’s) do?
Worked with pea plants. He studied a large number of characteristics e.g. wrinkled seeds. He used pure breeding lines of seeds (always produce particular traits) which he then used to do his hybrid plant experiments. He did a large number of trials using artificial pollination. He made an exact count of offspring to study the identifiable traits. His work showed that traits not present in one generation could appear in later generations e.g. recessive.
what is law of random segregation?
allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. Each of the halpoid gametes only gets of the particular allele.
What did mendel discover?
He discovered that traits can be dominant or recessive and discovered a principle of heredity: the law of random segregation
Charles Darwin (1850s)
Proposed theory of evolution by natural selection. Wrote “Origin of Species” which had heaps of evidence in it. This enraged the Catholic Church. Theory states organisms most adapted to their environment survive and pass their favourable traits on to their offspring.
Alfred Wallace (1850s)
Independently proposed evolution by theory of natural selection.
What did George Beadle and Edward Tatum (1941) do?
- grew bread mould on material that has the minimium materials needed to survive.
- Exposed it to x-rays causing mutations.
- Discarded mould that continued to grow on minimum medium, instead wanting mould that didn’t grow.
- They found that the mould would grow when given one amino acid, showing that one chemical reaction had been stopped.
- This showed one enzyme was damaged by the mutation. Showed that one gene coded for one enzyme (or protein).
- Later changed to one gene-one polypeptide because it was discovered that many proteins are made more than one polypeptide.
What was the importance of sutton’s work?
Showed how important chromosomes are and explained the reasons for Mendel’s results with the information he found regarding genes being on chromosomes
What was the importance of Boveri’s work?
Showed importance of chormosomes and not all the same.
What were the contributions of James Watson and Francis Crick (1953)
Used model building to figure out the structure of DNA. Had slow progress until they used Franklins “photo 51” x-ray crystallography image of double helix DNA structure to produce an accurate model of DNA.
- Used to show that communication and collaboration are vital in science. They may have achieved better results quicker if all worked together.
- The close collaboration between Watson and Crick who had a good relationship, with the aid of Wilkins, enabled them to determine and publish their DNA model first.
- collaboration and communication are vital because it can take advantage of people’s specific skills, enabling developments to happen more quickly.
What were the contributions of Rosalind Franklin and Maurice Wilkins (1953)?
Franklin was a successful female scientist who used x-ray crystallography to image DNA. The image (photo 51) was clear and accurate showing that DNA was a double helix.
Wilkins was x-ray crystallographer also trying to discover structure of DNA. The two did not work well together. Wilkins gave Franklin’s work to Watson and Crick. The two made almost no progress on structure of DNA when working together.
Outline the experiments conducted by Beadle and Tatum
Beadle and Tatum exposed bread mould to xrays causing mutations. They discovered that the mutations required additional supplements to survive, unlike their normal counterparts, highlighting how a single genetic mutation can incapacitate specific enzymes (which would have normally provided these supplements). Their experiments led to the understanding that one gene produces one enzyme.
Why was the one gene, one enzyme theory changed to one gene, one polypeptide?
Found to be false in certain proteins, eg. haemoglobin which has 4 polypeptides chains, whith each chain type controlled by a different gene, New statement more accurate.
What were Franklin’s experiences and what did they highlght?
- She worked well by herself and clashed with Wilkins, who gave her image to Watson who then gave it to Crick against her wishes.
- She was not allowed to college discussions and was treated as inferior due to her gender.
- Franklins kept her results secret, which may have caused her to not publish them in time for her discovery to be acknowledged.
- Franklins never received due credit for her work, (died of ovarian cancer before nobel prize was awarded) and highlights the poor treatment that female scientists received during that period.
What are the chemical components of a CHROMOSOME?
DNA and protein
The Gamete plays an important role in sexual reproduction because it carries
HALF of the genetic info of the parent
Outline the work done by Morgan that has led to our understanding of sex linkage
Morgan bred fruit flies (drosophila) and observed that the eye colour was not inherited in normal Mendelian ratios. He identified that the white eye colour was common in males and rare in females. He went on to suggest that this occurred because the gene is carried on a sex chromosome that the females get two copies of and the males get one copy of.
What are the main steps of DNA replication?
- The double stranded DNA is unzipped by an enzyme breaking the hydrogen bonds of the bases.
- The resulting exposed bases pair up with complementary free nucleotides in the nucleus .
- Resulting process leaves two strands of identical copies of the original DNA strand.
Why is variation in a species needed?
Variation enables a species to change over time which is particularly advantageous to a species in a changing environment.
Distinguish btw gene and allele
A gene is a section of DNA that contains the instructions to make a polypeptide. The gene has a specific location on a chromosome. Genes control a characterisitic eg. Eye colour, blood type etc. An allele is the alternative form or variation of this characteristic or gene, eg. Brown/blue or A/O
Describe the contributions of Boveri, Sutton and Morgan
Boveri showed that chromosomes are separate, continuous entities within the nucleus of a cell and that cells with the correct number of chromosomes were able to develop normally
Sutton proposed the chromosomal theory of inheritance, and suggested that Mendel’s inheritance factors are located on chromosomes. He demonstrated the principles of segregation and random assortment using grasshoppers
Using drosophila, Morgan demonstrated that some genes are carried on the X chromosome and others on the Y chromosome leading to an awareness that some genes are sex-linked.
What Is the definition of genetic engineering?
Any technique used to alter/change genetic makeup of cells or organisms by inserting, removing or modifying individual genes
Traditionally done by interbreeding *
What are methods of genetic engineering? And what happens?
- Selective breeding: breeding of individuals with desired characteristics only–> sometimes result in new variety of animals
- Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male –> can decrease genetic diversity however, as desirable characteristic chosen
- Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep: - DNA was removed from an unfertilised egg
2.udder cell from sheep - Fuse cells + culture
- Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
What are methods of genetic engineering? And what happens?
- Selective breeding: breeding of individuals with desired characteristics only–> sometimes result in new variety of animals
- Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male –> can decrease genetic diversity however, as desirable characteristic chosen
- Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep: - DNA was removed from an unfertilised egg
2.udder cell from sheep - Fuse cells + culture
- Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
What are methods of genetic engineering? And what happens?
- Selective breeding: breeding of individuals with desired characteristics only–> sometimes result in new variety of animals
- Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male –> can decrease genetic diversity however, as desirable characteristic chosen
- Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep: - DNA was removed from an unfertilised egg
2.udder cell from sheep - Fuse cells + culture
- Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
What are methods of genetic engineering? And what happens?
- Selective breeding: breeding of individuals with desired characteristics only–> sometimes result in new variety of animals
- Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male –> can decrease genetic diversity however, as desirable characteristic chosen
- Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep: - DNA was removed from an unfertilised egg
2.udder cell from sheep - Fuse cells + culture
- Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
What is a locus?
The actual place on the chromosome where an allele is found
What are methods of genetic engineering? And what happens?
- Selective breeding: breeding of individuals with desired characteristics only–> sometimes result in new variety of animals
- Artificial pollination and insemination
Artificial pollination: breeder stops self pollination in plants by removing stamens(stop self pol +insect pol.)
He then places pollen from desired plant of choice on the stigma of the flower, delicate and done with tweezers.
After pollination, flower is covered to protect it from contamination of unwanted Pollen
Artificial insemination:
Used in agriculture. Semen is collected from male animal. (Is then frozen to be stored for long time)
Then it is defrosted and inserted into cervix of female animal why she is ovulating. Large number of females can be impregnated by one male –> can decrease genetic diversity however, as desirable characteristic chosen
- Cloning: genetically identical cells/individuals
-plants clone through asexual means
in dolly the sheep: - DNA was removed from an unfertilised egg
2.udder cell from sheep - Fuse cells + culture
- Implant in surrogate mother
*DNA must be removed from gamete to clone
The nucleus from body cell provided genes for phenotype
Name a fact that about the process of Dna replication that provides support for Darwin’s theory of evolution
mutations of DNA may lead to new alleles.
Discuss the beneficial social and environmental impact of a transgenic species
(b) Bt corn is an example of a transgenic species created by scientists.
- more profitable crops and more productive, provides a sustainable food source for populations
- It provides a benefit to society as it reduces the need to spray cotton crops with insecticides. This saves people time and money.
- beneficial as pesticides can kill microbial soil life, which can lead to unsustainable farming practices.
- An advantage to the environment is that Bt cotton reduces the use of insecticides, reducing runoff and the impact of health of surrounding flora and fauna
- research indicates that gm corn has no little/no affect on health (no correlation between increase in disease and increased consumption of BT corn.
Define environment
Environment is everything around you including living and non living factors, has physical and chemical conditions.
Distinguish between physical and chemical conditions
physical conditions (temp, humidity, rainfall, wind speed) and chemical conditions (pH of soil/water, salt concentrations)
Eg of how a change in physical conditions can impact evolution of animals, leading to changes in a species.
Peppered moth-originally light colour to camouflage against tree trunks.
industrial revolution trunks became covered in soot, Moth no longer camouflaged +more visible to predators (birds)- decreased in numbers.
The mutated black form of the moth increased in numbers -had better camouflage and could better survive predation.
after industrial revolution, more pale moths became prominent
What 5 areas of study support the theory of evolution
palaeontology biogeography biochemistry comparative embryology comparative anatomy
What method was used to model natural selection (the aim)
- Cut out 30 (0.5x0.5) pieces black paper & 30 white pieces.
- Scatter randomly over A3 white paper.
- Have 1 individual select as many pieces possible in 10sec-use timer
- Replace so that offspring produced are 1/2 the number of offspring remaining (Eg. if 20 white were taken, only 10 would remain so offspring for white would be 5)
- Repeat steps 3. & 4., then record results.
What was the conclusion for modelling natural selection?
the greater selection of black paper suggests the model was successful in achieving aim of modelling natural selection. In a predatory-prey relationship those of the prey that are more camouflaged more likely to survive than the more visible members.
What was a benefit of the model for natural selection?
• Can be done in short period of time while in nature would take years
• Visual so colours representing variations in population - easy to see changes
• All processes in natural selection modelled
- Accessible resources
-simple method so a clear general understanding gained
-Time frame of 10sec places pressure on individual so there bias is less likely, they just select what is immediately visible.
What was limited the model for natural selection?
Oversimplified.
• Predation only method of members being removed from population while some may naturally die etc
• Only one type of variation shown (ie colour)
• All mating result in offspring
-there are other selection pressures not just one, (change in chemical conditions, comp for resources),
-black and white strips could interbreed, initially altering rate of natural selection
-the selection pressure is unclear, an important step in Darwin/Wallace’s theory.
-Doesn’t reflect the longer time period of natural selection, giving a slightly distorted understanding.
How does archaeopteryx support the theory of evolution?
it had reptilian features (clawed fingers, teeth, bony tail) and skeleton, but feathers,wings and wish bone for flight like a bird
Shows evidence for evolutionary pathway from dinosaurs to birds.
